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Shortwave random-wire antenna question

D

Dave

Jan 1, 1970
0
An idea just occurred to me. Since you (RHF) are the main one I am talking
with on this subject at this point, and since I did join the Yahoo!
Shortwave Antenna group, I am going to try (that is, do my best) to move
this over to that group. All posts from this point on, at least on this
particular thread, will be made there. This text will be posted there in a
few minutes, alongwith a couple more questions and clarifications.

Thanks for introducing me to that group, which I am trying to get more
into, and thanks for your help so far.

Dave
[email protected]

RHF said:
= = = "Dave said:
Argh. I just posted an empty message. Sorry. Please ignore.

Thanks for the info. I picked up a 300/75 ohm mini-plug adapter at the
store, but failed to get the second 75/300 ohm matching transformer to go
between it and the coax. Tomorrow.

Question: I have an odd situation, and can either install a 1/4 wave dipole
or a half-wave "random" wire loop (I think).

A "Random" Wire Antenna is simply that = Any Length that FITS
the Space that is Available to put up and Antenna.

For these general types of Low Noise Antennas. The Inverted "L"
{Shaped} Antenna lends itself to the design the best.

Run the Horizontal Arm for as long as you can at your roof line.

Run the Vertial Leg down to your Ground Rod Location.

Make your 'primary' Grounding Point "Connection".

Run your Coax Cable from the Grounding Point to your Radio.
.
.
Right now the grounding rod is immediately below where the
dipole would go, and I think I could drop the 300 ohm twin-lead
down to it where I would ground one side (I think I have
this right, please correct me if I am wrong).

Initially do NOT Ground the 300 Ohm Twin Lead.
[ This is the Antenna Side of the Matching Transformer. ]
The Near-End of the 300 Ohm Twin Lead is connected across the
300 Ohm-Side of the Matching Transformer; and the other Far-End
of the 300 Ohm Twin Lead Wires are Connected (Joined) Together.
This forms a Long Shinny Loop Antenna Element.

FWIW: This is a very 'quiet' Antenna (almost sounds dead)
until you get spot on the frequency and then the signal is there.
.
.
At that same point I would ground the shield of the coax,
and hook the other side of the dipole to the coax center conductor.
Coax would travel 10 feet or so to my window and the radio.

First simply try Grounding the Outer-Shield of the Coax Cable ONLY.
.
.
Other option involves moving the grounding rod

IF - You move the Ground Rod. Place it so you can have an
Inverted "L" Antenna with the longest Horizontal Arm 'possible'.
(30 <60-90> 120 Feet)

iane ~ RHF
.
.
and doing something similar with the twin-lead as a long loop,
grounding one side of that and coax from the other side of the window.
Assuming these are workable ideas,
which do you think would work best? Again, [please don't hesitate to tell
me if I am full of crap. RF is new to me.

I really do appreciate your help. Like I said before, RF is totally new to
me.

Thanks,

Dave
[email protected]
 
C

CW

Jan 1, 1970
0
And what of the people just fallowing along? Don't suggest Yahoo. It's not
an option.

Dave said:
An idea just occurred to me. Since you (RHF) are the main one I am talking
with on this subject at this point, and since I did join the Yahoo!
Shortwave Antenna group, I am going to try (that is, do my best) to move
this over to that group. All posts from this point on, at least on this
particular thread, will be made there. This text will be posted there in a
few minutes, alongwith a couple more questions and clarifications.

Thanks for introducing me to that group, which I am trying to get more
into, and thanks for your help so far.

Dave
[email protected]

RHF said:
= = = "Dave said:
Argh. I just posted an empty message. Sorry. Please ignore.

Thanks for the info. I picked up a 300/75 ohm mini-plug adapter at the
store, but failed to get the second 75/300 ohm matching transformer to go
between it and the coax. Tomorrow.

Question: I have an odd situation, and can either install a 1/4 wave dipole
or a half-wave "random" wire loop (I think).

A "Random" Wire Antenna is simply that = Any Length that FITS
the Space that is Available to put up and Antenna.

For these general types of Low Noise Antennas. The Inverted "L"
{Shaped} Antenna lends itself to the design the best.

Run the Horizontal Arm for as long as you can at your roof line.

Run the Vertial Leg down to your Ground Rod Location.

Make your 'primary' Grounding Point "Connection".

Run your Coax Cable from the Grounding Point to your Radio.
.
.
Right now the grounding rod is immediately below where the
dipole would go, and I think I could drop the 300 ohm twin-lead
down to it where I would ground one side (I think I have
this right, please correct me if I am wrong).

Initially do NOT Ground the 300 Ohm Twin Lead.
[ This is the Antenna Side of the Matching Transformer. ]
The Near-End of the 300 Ohm Twin Lead is connected across the
300 Ohm-Side of the Matching Transformer; and the other Far-End
of the 300 Ohm Twin Lead Wires are Connected (Joined) Together.
This forms a Long Shinny Loop Antenna Element.

FWIW: This is a very 'quiet' Antenna (almost sounds dead)
until you get spot on the frequency and then the signal is there.
.
.
At that same point I would ground the shield of the coax,
and hook the other side of the dipole to the coax center conductor.
Coax would travel 10 feet or so to my window and the radio.

First simply try Grounding the Outer-Shield of the Coax Cable ONLY.
.
.
Other option involves moving the grounding rod

IF - You move the Ground Rod. Place it so you can have an
Inverted "L" Antenna with the longest Horizontal Arm 'possible'.
(30 <60-90> 120 Feet)

iane ~ RHF
.
.
and doing something similar with the twin-lead as a long loop,
grounding one side of that and coax from the other side of the window.
Assuming these are workable ideas,
which do you think would work best? Again, [please don't hesitate to tell
me if I am full of crap. RF is new to me.

I really do appreciate your help. Like I said before, RF is totally
new
 
D

Dave

Jan 1, 1970
0
Okay, I'll try to keep you posted. Here's what I asked on Yahoo!

OKAY, here are the new questions and clarifications...

Thanks for clearing up for me why it is called a random wire. I
thought that was just what they called it when it wasn't 1/4 or 1/2
wavelength.

I realized something today- I think I am actually talking about
installing a HALF-WAVE dipole, not a 1/4 wave. Since it is twin-lead
I am talking about, and since it is going to be joined at the far
end, each leg would be twice the 1/4 wavelength of the physical
cable. Am I right here?

Correct me if I am wrong, but you do ground one side of a dipole,
right? So one leg would be grounded along with the shield of the
coax, right?

What I am visualizing is two pieces of twin-lead, one called A (left)
and the other called B (right.) A would have one side of one end
soldered to the ground rod (call this the "near" end) with the other
side of that end hanging out in space. The rest of that piece of
twin-lead (side A) would go up the side of my house to the eaves and
over several meters. The far end of A would have the two conductors
soldered together. B would have one side of the "near" end attached
to the appropriate lead of a 300/75 ohm matching transformer, which
has it's other lead soldered to the grounding rod and goes to 75 ohm
coax. The other side of the "near" end of B hangs out in space. B
would then go up the side of the house to the eaves, just like A, but
would then stretch several meters in the other direction. The "far"
end of B would also have the two conductors soldered together. Each
leg is a little over 15 meters long (counting the part that goes up
as well as the part that goes over), which would make the whole
dipole a half-wavelength for some frequency slightly below 10 MHz.
(Have I got this right?)

The coax would travel approx. 4 meters to my window, where it would
go through another matching transformer and into the external antenna
input of the radio.

Wouldn't that be a half-wave dipole?

Would it matter that the side of the house is covered in steel
siding, against which it would be lying?

Would this work, or would an inverted L still be better (or
quieter)? I could put the grounding rod immediately outside my
window, which might enable me to make the long leg of the L somewhat
longer than the combined 30 meters of the dipole. That would make
for a shorter run of coax, but the soil would be drier thereby making
for a poorer ground (where it is now, the grounding rod sits next to
the output of a downspout.)

If I went with the inverted L (with joined conducters on the far end
to make a loop) would I still ground one side of the twin-lead? Do
you ground one side of a loop?

Okay, I've written War and Peace. Sorry for the great number of
questions, I'm just trying to understand the fundamentals of
installing an antenna. I hope I am not trying your patience.

Thanks,

Dave


I also posted another message asking if anyone had read the book called
Shortwave Listener's Antenna Handbook published by TAB books in '82. I saw
it on Amazon.com, but they didn't have any ratings for it. If anyone HERE
has read it, please share your opinion with me.

Dave
[email protected]

CW said:
And what of the people just fallowing along? Don't suggest Yahoo. It's not
an option.

Dave said:
An idea just occurred to me. Since you (RHF) are the main one I am talking
with on this subject at this point, and since I did join the Yahoo!
Shortwave Antenna group, I am going to try (that is, do my best) to move
this over to that group. All posts from this point on, at least on this
particular thread, will be made there. This text will be posted there
in
a
few minutes, alongwith a couple more questions and clarifications.

Thanks for introducing me to that group, which I am trying to get more
into, and thanks for your help so far.

Dave
[email protected]

RHF said:
= = = Argh. I just posted an empty message. Sorry. Please ignore.

Thanks for the info. I picked up a 300/75 ohm mini-plug adapter at the
store, but failed to get the second 75/300 ohm matching transformer
to
go
between it and the coax. Tomorrow.

Question: I have an odd situation, and can either install a 1/4
wave
dipole
or a half-wave "random" wire loop (I think).

A "Random" Wire Antenna is simply that = Any Length that FITS
the Space that is Available to put up and Antenna.

For these general types of Low Noise Antennas. The Inverted "L"
{Shaped} Antenna lends itself to the design the best.

Run the Horizontal Arm for as long as you can at your roof line.

Run the Vertial Leg down to your Ground Rod Location.

Make your 'primary' Grounding Point "Connection".

Run your Coax Cable from the Grounding Point to your Radio.
.
.
Right now the grounding rod is immediately below where the
dipole would go, and I think I could drop the 300 ohm twin-lead
down to it where I would ground one side (I think I have
this right, please correct me if I am wrong).

Initially do NOT Ground the 300 Ohm Twin Lead.
[ This is the Antenna Side of the Matching Transformer. ]
The Near-End of the 300 Ohm Twin Lead is connected across the
300 Ohm-Side of the Matching Transformer; and the other Far-End
of the 300 Ohm Twin Lead Wires are Connected (Joined) Together.
This forms a Long Shinny Loop Antenna Element.

FWIW: This is a very 'quiet' Antenna (almost sounds dead)
until you get spot on the frequency and then the signal is there.
.
.
At that same point I would ground the shield of the coax,
and hook the other side of the dipole to the coax center conductor.
Coax would travel 10 feet or so to my window and the radio.

First simply try Grounding the Outer-Shield of the Coax Cable ONLY.
.
.
Other option involves moving the grounding rod

IF - You move the Ground Rod. Place it so you can have an
Inverted "L" Antenna with the longest Horizontal Arm 'possible'.
(30 <60-90> 120 Feet)

iane ~ RHF
.
.
and doing something similar with the twin-lead as a long loop,
grounding one side of that and coax from the other side of the window.
Assuming these are workable ideas,
which do you think would work best? Again, [please don't hesitate
to
tell
me if I am full of crap. RF is new to me.

I really do appreciate your help. Like I said before, RF is totally
new
 
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